EVIDENCE FOR 2 EXPONENT SCALING IN THE RANDOM-FIELD ISING-MODEL

Novel methods were used to generate and analyze new 15 term high temperature series for both the (connected) susceptibility chi and the structure factor (disconnected susceptibility) chi(d) for the random field Ising model with dimensionless coupling K=J/kT, in general dimension d. For both the bimodal and the Gaussian field distributions, with mean square field J2g, we find that (chi(d)-chi)/K2gchi2=1 as T --> T(c)(g), for a range of [h2]=J2g and d=3,4,5. This confirms the exponent relation gammaBAR=2gamma (where chi(d) is similar to t(-gammaBAR), chi is similar to t(-gamma), t=T-T(c)) proving that random field exponents are determined by two (and not three) independent exponents. We also present new accurate values for gamma.